You’ll often see the terms design system, pattern library, and style guide used interchangeably.

The three concepts are connected but definitely not the same.

Let’s clarify definitions, visualize how they fit together, and discuss the major milestones in building a design system.

Design system definitions

First, let’s get the definitions straight so we can learn how our concepts are connected and how they can be used to create better products.

Design System – the complete set of design standards, documentation, and principles along with the toolkit (UI patterns and code components) to achieve those standards.

Pattern Library – A subclass in the design system, this is the set of design patterns for use across a company.

Style guide – Another subclass in the design system, this static documentation describes the design system itself: how products should look and feel, use cases for UI patterns, correct typographic scales, etc.

Bottom line: A pattern library (e.g. set of symbols and assets in Sketch) and style guide are only parts of the much more robust design system.

How it all connects

First, keep your focus broad and think about the idea of design systems.

At the broadest level, a design system is a living entity containing the common linguistics, principles, and tools to help teams build products coherently. As Nathan Curtis says, a “design system isn’t a project, it’s a product serving products”.

Product principles – What is the purpose and soul behind all the products?

Written content – How should the product’s interface copy look and feel?

Visual properties– What should the “skin” of the product look and feel like?

Components– What are the UI patterns and code components needed to build products coherently across devices?

Shopify’s Polaris Design System.

In this case, Polaris is the complete design system of principles, written content, visual properties, and components. The style guide is simply the static documentation on the Polaris website which describes how to use the design system. The pattern library is part of the “Components” in the Polaris design system.

The differences are subtle but unmistakably important when it comes to improving product development. A style guide on its own becomes quickly outdated since documentation requires maintenance. A pattern library lacks the instructions and principles for coherent implementation.

1. Create the UI inventory: First list and describe all of the design patterns currently used in your interface and note the inconsistencies therein.

2. Get support of the organization: Present your findings and explain the utility of a common design language to everyone. As explained in our Evangelizing Design Systems templates, estimate the number of design and engineering hours wasted on redundant work and how product coherence can improve NPS scores.

3. Establish design principles: Codify your practices. You’re now starting to work on the style guide for the design system.

4. Build the color palette: When building the UI inventory, we found 116 different shades of grey that needed consolidation. Create the palette and its naming convention.

5. Build the typographic scale: You can optimize the scale to serve existing styles, or you might try to build a harmonious scale using the golden ratio or major second. When building the scale, don’t forget that you’re not only setting the size of the font, but also weight, line-height and other properties.

6. Implement icons library and other styles: Decide which icons from the UI inventory will become part of the design system, then standardize the implementation.

7. Start building your first patterns: This is the task that will never end. Patterns should always either reflect the truth about the product, or reflect the aspirational state of the product in the near future.

Next steps

We’ve defined and organize the terms design system, style guide, and pattern library into a hierarchical structure. We’ve also quickly described how to build your own design system.